In the process of oil and gas exploration and development, the oil and gas industry needs to accurately characterize the rock physical characteristics of underground reservoirs, so as to evaluate the storage capabilities of the underground reservoirs, judge the economic values of the underground reservoirs, determine the exploration and development strategies of the underground reservoirs, and improve the accuracy and economic benefits of the oil and gas exploration. The rock physical characteristics mainly include porosity, permeability, and pore structure. Therefore, it has a great guiding significance for the oil and gas exploration and development to accurately characterize the rock physical characteristics of reservoirs.
Carbonate reservoirs are one of the main oil and gas reservoirs, and the carbonate reservoirs having rock components easily affected by later diagnoses are complex in storage space and diverse in pore structure. Therefore, it is very difficult to effectively characterize the rock physical characteristics of the carbonate reservoirs. With continuous improvements on the oil and gas exploration technology, deeply buried carbonate oil and gas reservoirs having the buried depths of more than 4500 meters have received more and more attentions. Compared with medium-shallow reservoirs having the buried depths of less than 4500 meters, the deeply buried carbonate reservoirs have the characteristics of deep burial depth, low porosity and permeability and more complex pore structure. Therefore, it is quite difficult to effectively characterize the rock physical characteristics of the deeply buried carbonate reservoirs.
In terms of how to accurately characterize the rock physical characteristics of deeply buried carbonate reservoirs, the traditional methods for characterizing the rock physical characteristics of a medium-shallow reservoir are usually adopted in the prior art. For example, the rock physical characteristics are characterized by measuring the core characteristics of a cored segment, including observing thin sections to qualitatively describe the pore structure, semi-quantitatively analyzing the pore morphology and chemical components via a scanning electron microscope, or quantitatively obtaining micro-scale CT slices via high-precision CT scanning experiments to reconstruct a three-dimensional microscopic pore structure. However, since the deeply buried carbonate rocks have quite complex pore structure and extremely strong heterogeneity, the traditional methods cannot accurately characterize the rock physical characteristics of the deeply buried carbonate rocks, and then the developmental characteristics of the deeply buried carbonate reservoirs cannot be accurately evaluated.